(1) Field of the Invention
The present invention relates to a delivery apparatus in a machine for preparing plastic hollow vessels. More particularly, in a machine for preparing a plastic hollow vessel by heating a plastic preform at a drawing temperature and draw-blow-forming the heated preform in a split mold, the present invention relates to an apparatus for performing the delivery of the preform and vessel smoothly
(2) Description of the Prior Art
A biaxially draw-blow-formed vessel of a thermoplastic polyester such as polyethylene terephthalate (PET) has excellent transparency and surface gloss and has high impact resistance, rigidity and gas-barrier property required for a bottle, and therefore, this vessel is widely used for packaging various liquids.
In preparing a biaxially draw-blow-formed vessel of this type, there is adopted a process in which a bottomed preform is formed by injection molding of a plastic material, the bottomed preform is heated at a drawing temperature and the preform is draw-blow-formed in a split mold.
Japanese Patent Publication No. 45524/86 discloses an apparatus for preparing drawn plastic hollow vessels, which comprises;
a mandrel for supporting a preform composed of a plastic material and a hollow vessel formed from the preform; PA1 a loading zone for loading the preform on the mandrel; PA1 a preheating zone having a turret comprising a plurality of supporting seats for supporting the mandrel around the periphery thereof and a heating mechanism arranged along the periphery of the turret to heat the preform loaded on the mandrel; PA1 a blow-forming zone comprising a rotary member having, arranged along the periphery thereof, a plurality of openable and closable blow-forming molds and mandrel-supporting members corresponding to said molds; PA1 a delivery zone for delivering the preheated preform-loaded mandrel to the blow-forming zone from the preheating zone; PA1 a withdrawal zone for withdrawing the blow-formed vessel-loaded mandrel from the blow-forming zone; and PA1 an endless mandrel-delivering path which passes through the loading zone, the preheating zone, the delivery zone, the blow-forming zone and the withdrawal zone in the recited order. PA1 a mandrel for supporting a preform composed of a plastic material and a hollow vessel formed from the preform; PA1 a loading zone for loading the preform on the mandrel; PA1 a preheating zone having a turret comprising a plurality of supporting seats for supporting the madrel around the periphery thereof and a heating mechanism arranged along the periphery of the turret to heat the preform loaded on the mandrel; PA1 a blow-forming zone comprising a rotary member having, arranged along the periphery thereof, a plurality of openable and closable blow-forming molds and mandrel-supporting members corresponding to said molds; PA1 a delivery zone for delivering the preheated preform-loaded mandrel to the blow-forming zone from the preheating zone; PA1 a withdrawal zone for withdrawing the blow-formed vessel-loaded mandrel from the blow-forming zone; and PA1 an endless mandrel-delivering path which passes through the loading zone, the preheating zone, the delivery zone, the blow-forming zone and the withdrawal zone in the reacted order; PA1 wherein a preform supply mechanism for supplying the preform, a preform-loading and vessel-unloading mechanism for pushing the preform coming from the supply mechanism into the mandrel to fix the preform thereto and withdrawing the vessel from the vessel-loaded mandrel supplied from the withdrawal zone, a preform delivery mechanism for delivering the preform-loaded mandrel to the preheating zone and a vessel delivery mechanism for delivering the vessel withdrawn from the mandrel to the outside of the apparatus from the loading and unloading mechanism are arranged in the loading zone; PA1 said preform-loading and vessel-unloading mechanism comprises a first rotary member, a clamping mechanism having grippers arranged equidistantly along the periphery of said first rotary member to hold the neck portions of the preform and vessel, an opening and closing mechanism for opening and closing the grippers of the clamping mechanism, a reciprocating drive mechanism for driving the clamping mechanism reciprocatively in the axial direction of said first rotary member, a second rotary member arranged coaxially with said first rotary member below said first rotary member and spaced therefrom in the axial direction, and mandrel-supporting seats arranged equidistantly along the periphery of the second rotary members and located at positions coaxial with the positions for gripping the neck portions of the preform and vessel in the clamping mechanism; PA1 the preform supply mechanism, the preform delivery mechanism, the vessel withdrawal zone and the vessel delivery mechanism are arranged in the recited order in the rotation direction of the loading and unloading mechanism along the periphery of the loading and unloading mechanism; and PA1 the opening and closing mechanism and reciprocating drive mechanism for the clamping mechanism are combined with each other so that; PA1 at the contact point between the preform supply mechanism and the loading and unloading mechanism or in the vicinity thereof, the grippers are closed to hold the preform; PA1 in the region of from the contact point between the preform supply mechanism and the loading and unloading mechanism to the contact point between the preform delivery mechanism and the loading and unloading mechanism, the movement for insertion of the preform into the mandrel is carried out; PA1 at the contact point between the preform delivery mechanism and the loading and unloading mechanism or in the vicinity thereof, the grippers are opened to release the preform; PA1 at the contact point between the vessel withdrawal zone and the loading and unloading mechanism or in the vicinity thereof, the grippers are closed to hold the neck portion of the vessel; PA1 in the region of from the contact point between the vessel withdrawal zone and the loading and unloading mechanism to the contact point between the vessel delivery mechanism to the contact point between the vessel delivery mechanism and the loading and unloading mechanism, the movement for the withdrawal of the vessel is carried out; PA1 at the contact point between the vessel delivery mechanism and the loading and unloading mechanism or in the vicinity thereof, the grippers are opened to release the vessel; and PA1 in the region of from the contact point between the vessel delivery mechanism and the loading and unloading mechanism to the contact point between the preform supply mechanism and the loading and unloading mechanism, the half-turn movement of the clamping mechanism is carried out.
In a plastic hollow vessel-preparing apparatus of this type, the operation of inserting the preform into the mandrel and fixing the preform to the mandrel and the operation of withdrawing the formed vessel from the mandrel are necessary and indispensable.
Furthermore, since support rings are formed on the neck portions of the preform and vessel for supporting them, the preform and hollow vessel are delivered in the state where the mouth portions are located on the upper side. Accordingly, prior to the above-mentioned inserting and fixing operation, the operation of turning over the preform should be performed, and after the above-mentioned withdrawal operation, the operation of turning over the vessel should be performed.
In the above-mentioned conventional apparatus, since the operation of inserting and fixing the preform and the operation of withdrawing the formed vessel are carried out by different mechanisms, the structure of the apparatus is complicated, and if mechanisms for performing the operations of turning over the preform and the formed vessel are attached to the apparatus, the structure of the apparatus becomes more complicated